BRUSSELS, Sept 4 — Nato allies agreed today that Russia must cooperate fully with an impartial investigation to be led by the Organisation for the Prohibition of Chemical Weapons into the poisoning of opposition leader Alexei Navalny, the alliance’s chief said.

Germany, where Navalny is in hospital, has said he was poisoned with a Soviet-style Novichok nerve agent.

Russia has until now not opened a criminal investigation and said there is no evidence yet of a crime.

"Any use of chemical weapons shows a total disrespect for human lives, and is an unacceptable breach of international norms and rules,” Secretary General Jens Stoltenberg told a news conference.

"Nato allies agree that Russia now has serious questions it must answer. The Russian government must fully cooperate with the Organisation for the Prohibition of Chemical Weapons (OPCW) on an impartial international investigation,” he said, reporting back from a meeting of the alliance’s ambassadors.

Navalny is the most popular and prominent opponent of President Vladimir Putin, and the German announcement this week that he was poisoned by a nerve agent has raised the possibility of further Western sanctions against Moscow.

Stoltenberg said the Nato allies called on Moscow to provide complete disclosure of the Novichok programme to the OPCW.

"Those responsible for this attack must be held accountable and brought to justice. Time and again we have seen opposition leaders and critics of the Russian regime attacked and their lives threatened. Some have even been killed,” he said.

Describing the Navalny case as "an attack on fundamental democratic rights” as well as on an individual, he said Nato allies would continue to consult on the incident and "consider the implications”. — Reuters